Question

If 3 is zero of the polynomial p(x)=2x cube-3x+7a, from the value of a

Answer 1

Answer:

Explanation:

Given polynomial p(x)=2x  

2

−3x+7a is zero polynomial if x is 2

Replace x by 2 we get

∴2(2)  

2

−3(2)+7a=0

⇒2×4−3×2+7a=0

⇒8−6+7a=0

⇒2+7a=0

Add -2 both sides we get

2+7a−2=0−2

⇒7a=−2

Divided by 7 both side we get

a=−  

7

2

​

 

So a=−  

7

2

​

Answer 2

p(x)=2x³-3x+7a

p(3)=2(3)³-3(3)+7a=0

=>2(3)³-3(3)+7a=0

=>2×27-9+7a=0

=>2×27-9+7a=0

=>54-9+7a=0

=>45+7a=0

=>7a=-45

=>a=-5